Nearly a dozen Northern Ireland branches of high street travel agent TUI are at risk of permanent closure after it announced plans to shut 166 stores in the UK and Ireland.
TUI's move is the latest signal of the crisis sweeping the travel industry as a result of Covid-19.
The industry reacted with disappointment to the UK government's decision to impose a 14-day quarantine on tourists returning from Spain due to its growing level of coronavirus cases. The quarantine also covers Spain's Canary and Balaeric Islands.
TUI, the UK's biggest tour operator, announced it is shutting around one third of its total of 516 stores.
The decision was made following changes in customer behaviour, the firm said in a statement.
Around 350 retail stores will remain following the closures.
However, it would not comment on which Northern Ireland stores were at risk as a consultation is taking place.
Tory MPs are putting pressure on Prime Minister Boris Johnson to introduce coronavirus testing at airports to cut the 14-day quarantine.
And a group of 47 airlines, airports and tourism leaders - including Belfast International Airport chief executive Graham Keddie - have also called on the Prime Minister to introduce virus tests for those arriving in the UK.
TUI said stores which are have reopened since the pandemic are not at risk of closure.
But only one of its 12 Northern Ireland stores - a branch at Waterloo Place in Londonderry - have so far reopened.
The shutters remain down at branches in Armagh, Coleraine, Lisburn, Newtownards, Ballymena, Craigavon, Omagh, Dungannon and Newry - as well as two branches in Belfast's CastleCourt Shopping Centre and on Bloomfield Avenue.
The chain has 10 stores in the Republic and is based in Germany.
Andrew Flintham, managing director of TUI UK and Ireland, said: "We want to be in the best position to provide excellent customer service, whether it's in a high street store, over the telephone or online, and will continue to put the customer at the heart of what we do.
"It is therefore imperative that we make these difficult cost decisions, look after our colleagues during such unprecedented uncertainty and also offer a modern customer service."
TUI is the latest high street chain after bakery chain Greggs and bookseller Eason to indicate that it won't reopen at least some of its shops following lockdown.
Greggs is closing three of its 21 stores - while Eason has shut all seven of its remaining Northern Ireland stores.
Glyn Roberts, the chief executive of Retail NI, hoped TUI would provide clarification on which stores will be affected by the closure plans.
"It's fair to say that this was a company which was facing a significant challenge before Covid-19 due to the growth in online holiday bookings," he said.
"And in other businesses such as Eason which have also faced troubles before Covid, Covid-19 has now almost finished them off.
"There are not just the effects from the numbers of jobs lost in retailers, but closures like TUI and Eason also had a knock-on effect as footfall into the area is diminished."
The pandemic and lockdown have had a catastrophic effect on demand for overseas holidays, with many bookings cancelled after quarantine was introduced. Yesterday easyJet cancelled a number of its flights.
In a letter to Mr Johnson, the bosses of British Airways, easyJet and Jet2 demanded a more "nuanced" policy than the 14-day quarantine.
They called for the introduction of regional travel corridors to replace the blanket requirement of 14-day quarantine for anyone returning from an at-risk country.
Transport Secretary Grant Schapps cut his family holiday in Spain short as a result. As he returned to the UK, he defended the UK government's decision.
"I very much understand, it obviously had an impact on me and my family, and I'm very, very sorry and upset for the thousands of Brits who are either away or perhaps even haven't managed to go away this summer as well to Spain," he said.
"But it's absolutely essential we acted when we did, it's why all four nations of the UK acted together and the figures since have turned out to justify that action.
"We have to, I think, have a clear message and make sure we act by adding entire countries to that list for the time being."
People who test positive for coronavirus or display symptoms must now self-isolate for 10 days as Health Secretary Matt Hancock warned of a "second wave starting to roll across Europe".
The UK's chief medical officers said on Thursday that the period must increase from the current rule of seven days because of the risk individuals may still be able to spread Covid-19.
In a joint statement, they said the change for those who experience the key symptoms of a new continuous cough, high temperature or loss of taste or smell is needed because of the "low but real possibility of infectiousness" up to 10 days.
Their move came as official analysis said England had the highest levels of excess mortality in Europe across the first half of 2020.